It is necessary to disassemble and reassemble poppet valves in engine cylinder heads when rebuilding the engine and regrinding the valves and for other purposes such as replacing a broken or worn part. Many modern small engines have the spring assembly (spring/retainer washer/keeper and valve stem) recessed within a bore in the engine cylinder head. Recessed valve assemblies were designed to have less moving parts and to downsize engines. The cam rides directly above valves so there is no need for a rocker arm assembly or push rods. Lifters ride directly on top of the valve and the cams are seated oil top of the lifters. However, this compact arrangement makes it more difficult to disassemble and reassemble the valve for repair or replacement. U.S. Pat. No. 5,207,196 illustrates this type of compact engine cylinder head and one tool for inserting a preassembled valve unit when constructing the engine, as in the initial assembly of the engine at the factory.
While a number of tools have been proposed for use on earlier, more easily accessible valve stem assemblies (such as U.S. Pat. Nos. 5,375,308; 4,304,035; and 4,667,388) there exists a need for a simple tool that can allow the quick and easy disassembly, and aid in the more important and more difficult task of reassembly, of a bore-surrounded valve stem assembly at the repair shop without the need of using a preassembled total replacement unit.